A process-based framework for quantifying the atmospheric preconditioning of surface-triggered convection

Abstract

Here we introduce the heated condensation framework, which contains a suite of variables for isolating the atmospheric boundary state from local surface forcing. The buoyant condensation level (BCL) and buoyant mixing temperature (θBM) quantify the degree to which the atmosphere is preconditioned for moist convection and can be calculated for any time of day or year using standard vertical profiles of temperature and humidity. Unlike the lifted condensation level and convective inhibition, the BCL is constructed through incremental mixing from the surface rather than lifting a hypothetical parcel. In this regard, the BCL represents a conserved condensation level diagnostic inherent to a given profile. The BCL and θBM are shown to be applicable over a range of climate regimes and respond to synoptic and mesoscale forcings, illustrating its broader utility. A suite of variables relating the BCL directly to surface fluxes is also introduced. Key Points Presents a new framework that accurately captures convective triggering Framework metrics are inherent to profiles; not subject to parcel selection bias Heat and moisture necessary for triggering convection can be directly quantified ©2013. American Geophysical Union. All Rights Reserved.